This invention relates to improvements in paper processing machines such as in a paper making machine or a paper converting machine where the continuously traveling web is coated and particularly to where the web passes through a breaker nip and a coating nip with the operation of the breaker stack combined with the operation of a coating press in a combined unit apparatus.
Paper webs containing ground wood will require, if they are to be sized or precoated, that they first be passed through a breaker stack with chilled iron rolls. There is a current substantial trend toward replacing traditional 100% chemical furnish sheets with sheets containing various percentages of ground wood due to the lower furnish costs and also due to the higher yield from the wood and the possibility of using lighter basis weights for a given sheet caliper. For example, in computer printout paper, webs which were traditionally chemical furnish sheets have been used now containing on the order of 70% ground wood and 30% long fiber stock. This type of web requires passing through a size press before the final converting operation.
The reason for the requirement of the breaker press operation is that this results in a smoother sheet which will help control size pick-up and have increased ink hold-out. The web which has been passed through the breaker press also has the advantage of reducing fiber picking on the size press size applicator rolls which has been a problem with ground wood sheets.
Conventional breaker stacks employ 4 to 6 chilled iron rolls located between the top dryer can and the size press. These breaker press rolls require operational space and involve an open draw between the breaker press and the following size press. They also involve cost of construction and operation and provide operational hazards to the extent that the operator must be concerned with the mechanism during threading and tending of the machine.
It is an object of the present invention to provide an improved mechanism which will provide a combined breaker and coating or sizing operation avoiding disadvantages present with equipment heretofore available for those operations.
A further object of the invention is to provide an apparatus for a combined breaker stack and size press or coating operation reducing the overall space required for equipment heretofore available, reducing operational hazards to the machine tender or operator, reducing the expense of equipment needed, and reducing the parts and rolls required for the mechanism.
A still further object of the invention is to provide a breaker press and coating mechanism which will provide an improved web of paper eliminating the need for open draws or the length of draws necessary and providing for coating immediately following the breaker press operation reducing the time elapsed between the application of a breaker press into the web and the application of coating or sizing.
Other objects and advantages and features as well as equivalent structures and methods which are intended to be covered herein will become apparent with the teaching of the principles of the present invention in connection with the disclosure embodiments in the specification, claims and drawings, in which: